/**
 * LCR 105. 岛屿的最大面积
 * https://leetcode.cn/problems/ZL6zAn/description/
 */
class Solution2 {
    int m, n;
    boolean[][] vist;
    int ret, count;
    public int maxAreaOfIsland(int[][] grid) {
        m = grid.length;
        n = grid[0].length;
        vist = new boolean[m][n];
        for(int i = 0; i < m; i++) {
            for(int j = 0; j < n; j++) {
                if(grid[i][j] == 1 && !vist[i][j]) {
                    count = 0;
                    dfs(grid, i, j);
                    ret = Math.max(count, ret);
                }
            }
        }
        return ret;
    }
    int[] dx = {0, 0, -1, 1};
    int[] dy = {-1, 1, 0, 0};
    public void dfs(int[][] grid, int i, int j) {
        count++;
        vist[i][j] = true;
        for(int k = 0; k < 4; k++) {
            int x = i + dx[k], y = j + dy[k];
            if(x >= 0 && x < m && y >= 0 && y < n && !vist[x][y] && grid[x][y] == 1) {
                dfs(grid, x, y);
            }
        }
    }
}